Analysis On Thermal Equation Of Heliogreenhouse

In the condition of various natural climate, one adapt circumstance is created by the modern greenhouse for the plant is to achieve high efficiency, high quality, low cost, highly active profit and the goal of sustainable development. It's becoming a focus by people increasingly and being one important direction in the research. The winter produce of heliogreenhouse is with highly avail solar radiation energy source and controlling the microclimate environment to realize high energy conservational counter season produce. The controlling of greenhouse thermal environment is one of the most important aspect in each controlling factor, so the research on greenhouse thermal environment is becoming the key in the research of greenhouse microclimate environment.Base on describing quantificationally and analyzing different kinds of physical process in greenhouse, greenhouse climate model is mathematical formulation, which serves as a linkage between indoor climate and outdoor climate about the greenhouse. It's a kind of powerful instrument for greenhouse environmental control, design and science research.After absorbing advanced achievement from overseas, with the actuality of Chinese greenhouse establishment, the greenhouse climate model presented in this thesis is developed specifically for single-span greenhouse, which is the most common type in practice in North China. The model describes the basic physical processes such as thermal radiation, solar radiation, convection, conduction in the soil, evaporation from ground and condensation on the covering materials that govern the thermal environment of greenhouses and incorporates these physical processes into a dynamic model that can be used to predict thermal and mass fluxes among greenhouse components. The model is mathematically a group of ordinary differential and algebraic equations. The boundary conditions are outdoor temperature, relative humidity, solar radiation intensity. The main study and conclusion just as following:1. Collect and analyze the information on greenhouse microclimate model and thermal transmission, absorb some relational advanced fruits and experiences, made a definite thought about investigation and some questions should be noticed.2. Aim at mathematical models which have existed, it also made a systematic analysis on point of greenhouse thermal environment, mode of thermal transmission, condition of ambient and so on. Make some different between mathematics model and technic, and then it establish the thermal energy balance equation of greenhouse boundary layer configuration.3. During the five months experiment moment in the farmer's greenhouse, measured the data about indoor and outdoor of temperature, humidity, illumination, and then summarized the climatic change rules of in and out greenhouse. Collect the temperature of inner wall, soil, back-slope, surface of euphotic material and thermal energy density, which is in order to accumulate experimental data for establishing and checking the thermal energy balance model.4. Establish the thermal energy model about soil, wall, back-slope and surface of euphotic material, four parts in greenhouse, then solve the system of equations in the model and prove the model by software Matlab. Stimulant result indicate that the model can preferable simulate the thermal energy transmission in different boundary layer configuration. Compared with practical test and data, the result from the model has good coherence in veracity and uptrend, it has some reference value for greenhouse heat-insulating property design.5. Availing the result of thermal balance model, quantitative analysis thermal transmission and thermal loss instance of each greenhouse structure. Study and analyses the cause of greenhouse thermal loss, and then offer the feasibility optimize proposal. It's supplying some academic reference for optimizing greenhouse design in insulation structure.The study of greenhouse thermal environment model is a very complex, which is restricted by study condition and ambient condition, the model need to be consummated, and some parameters need to be analyzed optimality. So, this text made some study aimed at how to validate the model, and design a experiment project can be operated, it bring evidences for advanced development and validated experiments.